Uplock drive systems are used to operate a latching device for securely closing large doors such as in aircraft. The uplock drive is required to provide a reliable mechanical timing function to close the latch when the door reaches a precise location. The latch must be released at the proper time and held stationary while the door opens and closes.
The time allowed for latch actuation is extremely short. Therefore, means must be provided for controlled acceleration and deceleration of the output means or linkage to minimize inertial effects. Furthermore, due to the instantaneous actuation involved, the output linkage of the uplock system must be engaged at a precise location without the shock of a sudden engagement which might damage the shift mechanism used within the system. The precise angular positioning requirements preclude the use of any device which might slip during engagement.
In addition, it would be desirable for the system to provide a variable gear ratio in order to minimize the peak input torque. Output motion is constrained to a short fraction of the door actuation cycle. Therefore, the output velocity must be fast over most of a given range. A higher gear ratio is preferred during high values of output torque, which occur at a given, definite location. The output motion preferably should be of maximum torque at a specific time, with the output grounded at all other times on both sides of this period.
This invention is directed to providing a new and improved intermittent motion transmitting and timing system which fulfills all of the above requirements and desired parameters.